The present invention relates to an industrial truck with a charger, an asynchronous machine and a three-phase AC control unit, which converts a DC voltage of a battery for the asynchronous machine.
An industrial truck with a charging function is known from EP 1 350 664 A2, the entire contents of which is incorporated herein by reference, in which no separate charger is provided for recharging the battery, but an electronic control device which also controls the charging function. To this end, a separate voltage transformer with an AC/DC transformer is provided, which converts an applied mains voltage to the low voltage of the battery, the AC/DC transformer corresponding to a complete charger without a control board.
A three-phase AC drive arrangement is known from EP 0 849 112 A1, the entire contents of which is incorporated herein by reference, with a battery-supplied, rotational speed variable three-phase machine and a controlled pulse width modulation inverter which generates three-phase AC voltage for the three-phase machine. Furthermore, a charging device is provided for the drive battery, which is supplied by a three-phase network which charges the drive battery. This arrangement requires a motor of complicated design.
An on-board charger is known from EP 0 593 472 B1, the entire contents of which is incorporated herein by reference, in which two bridge arms of an inverter are controlled as step-up converters in order to apply a DC voltage to a capacitor and the further bridge arm of the inverter is controlled as a step-down converter in order to create a charging current for the traction battery from the capacitor.
JP 08 088 908 A, the entire contents of which is incorporated herein by reference, discloses a charger for an electrical railcar, in which secondary-side rectification is carried out in series by additional diode half-bridges.
A charger is known from JP 08 214 413 A, the entire contents of which is incorporated herein by reference, in which a power contactor is provided for switching between the three-phase AC control unit and the charger.
A combined motor drive and battery recharging system is known from U.S. Pat. No. 5,341,075, the entire contents of which is incorporated herein by reference, in which the applied mains voltage is not converted by a transformer but merely filtered.
The object of the invention is to provide an industrial truck with a charges for the traction battery which makes it possible to recharge the traction battery reliably and by simple means.